The Low-Down on Red Hat Enterprise Linux 5.1 Enhancements
Published: November 13, 2007
by Timothy Prickett Morgan
When commercial Linux distributor Red Hat announced it was going to take over the server world last week--well, half of it anyway--it also buried the rollout and update to its latest commercially supported Linux, Red Hat Enterprise Linux 5.1, inside the announcement. The details on what was new in RHEL 5.1 are a little scarce.
Here's the scoop on what is inside RHEL 5.1, which starts with the Linux 2.6.18-53 kernel. This new kernel release has improved ACPI power management support to step down power states on memory and CPUs. The SATA subsystem inside the kernel has been updated, and now the Ext3 file system supports file system sizes spanning up to 16 TB. InfiniBand support now includes Remote Direct Memory Access (RDMA) over Ethernet, which can significantly boost the speed with which information can be consumed by servers in InfiniBand switched fabrics. The IPv6 TCP/IP hooks in the kernel have also been tweaked for performance improvements with RHE 5.1.
On the virtualization front, RHEL 5.1 has been updated to the Xen 3.1.0 hypervisor, an update that allows Windows guests to be run atop the embedded Xen hypervisor inside the Linux platform. The libvirt management framework that is used with the Xen hypervisor has also been updated, and the AMD-V hardware-assisted virtualization features of the Opteron and Athlon processors from Advanced Micro Devices, called AMD-V, are now supported by the Red Hat variant of Linux, following existing support for Intel's similar VT features for its Core and Xeon processors. Red Hat has also tweaked its Linux to offer paravirtualized and fully virtualized guest operating systems on Itanium 2 processors, but it is not clear which hypervisor this is enabled for. (The odds strongly favor Hewlett-Packard's Virtual Server Environment, or VSE.)
RHEL 5.1 also has some new features that are available as a technology preview--meaning you should not roll them into production environments unless you are feeling dangerous. One such feature is support for 32-bit paravirtualized guest operating systems on 64-bit host systems based on AMD and Intel X64 processors. Red Hat is also adding "significant improvements" to the Global File System 2 file system and support for RHEL 5.1 as an iSCSI target device.
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